A known apparatus for electric induction heat treatment of thin strip material is illustrated in FIG. 1(a) and FIG. 1(b). A pair of induction coils 112a and 112b form a transverse flux inductor. Each coil has two transverse poles; coil 112a has poles 112a′ and 112a″, and coil 112b has poles 112b′ and 112b″. Thin strip 90 is positioned between the pair of coils. The thin strip may have a width, w1, for example, of 7/16th of an inch and a thickness, t1, of 0.01-inch. A single flux concentrator 114 is typically positioned over and around the two poles of each coil as shown in the figures. When a suitable alternating current (AC) is supplied to the pair of coils, a magnetic field is generated around the coil poles and the flux concentrators direct the magnetic flux towards the opposing surfaces of the thin strip so that it is inductively heated, for example, in an annealing or other metallurgical heat treatment process.
When the thin strip comprises a material with low resistivity (high conductivity) such as a copper strip, the arrangement shown in FIG. 1(a) and FIG. 1(b) is not very efficient.
It is one objective of the present invention to provide apparatus for, and method of, inductively heat treating a thin electrically conductive strip material, particularly when the strip material comprises a low resistivity composition such as copper.